POWERBOSS Motor Controller 6

[hd167]

Does anybody have experience with POWERBOSS Motor Controller (SOMAR Co. UK) for induction motors? It is not only a soft starter but adapts the voltage (current) to the real load requirements which results in energy savings especially during part load of the motor. I would learn the opinion of a user?

 

[freefallingbody]

Well, I'm not a user. However, I have evaluated ELECTROFLOW & POWERBOSS systems. For the applications where load is constant and above 30-40%, they don't make any sense if you want to save energy. They sometimes make sense if applied to machine tools ( where load comes only for a few cycles and having long idle time).

They are useful for giving you a soft start if you need one. Forget about energy saving!

 

[jbartos]

Suggestion: Visit

http://www.somars.com/powerboss_the_product.htm

etc. for more info

 

[busbar]

Search this site for "NOLA". Plenty of discussion.

 

[Marke]

Contrary to the claims of the manufacturers, you can only save some of the energy that is being wasted by the motor. The Iron loss for large motors is very small and so the savings are small also.
I have a paper at

http://www.lmphotonics.com/energy.htm

that covers this technology.
There have been many discussions on this topic on this and other forums.
Best regards,

Mark Empson

http://www.lmphotonics.com

 

[GGOSS]

Hello hd167,

Focus on the soft start feaures offered by these products and you'll be relatively pleased with your purchase.

If you purchase purely on the basis or energy savings, you'll most probably be dissappointed.

Regards,
GGOSS

 

[ozmosis]

The claims made by these companies often defy laws of physics. I have seen the claims "..30 to 40% energy savings" and many a company have been duped. The 30-40% savings relate to the FIXED LOSSES within an induction motor when the motor itself is effectively running at no or low load. When you really look at the energy savings, this may (if you are lucky), translate into a saving of about 1%. The other aspect to be very careful about is to establish the device you fit has a 'variable' optimising control (this is the technology that enables the controller to optimise the motor losses subject to the load). A lot of the low cost devices have a 'fixed' optimising controller that establishes the PF and output voltage at start-up when it gauges the load. If the load is a refrigeration pump, and the controller has 'fixed' itself,then serious problems will occur if the load changes and the only solution is the motor current goes up and, if you are lucky, the unit trips or the motor burns out.
As GGOSS says, focus on the benefits of reducing the starting current but if sized correctly (and it is a variable optimiser) then you can get some good energy savings on applications like refrigeration pumps.

 

[cbarn24050]

Hi, it depends on your application, you need to have your motor running off load for long periods in order to make any real saving. Small motors benefit most but as they dont use much energy it takes a long time to get your investment back. There are other benefits, the soft start puts less strain on the motor and drive train and your motor can run cooler so you may save on repair costs over the long term.

 

[ozmosis]

As 'cbarn24050' says, it depends on the application. A motor running at 70% load is quite typical in industry. The big question is, what is going to be your return on investment. Very little I would say. The efficiency of the controller is typically 97% and so you are going to lose 3% in real power if you keep the controller running all the time. Most people will by-pass a 'softstarter' once it has started to ensure they are not actually wasting energy during running. Look at the application more carefully and see what is going on. It might be more prudent to just switch the motors off if they are not doing much. There's a real reluctance to switch motors on and off due to the high starting currents, but if you are looking into softstarters, then switching the things off and on when needed (so long as it is not too regular) will save the most in energy.
If you want to calculate the 'savings' from your PowerBoss, we need to look at your motors (22 to 75kW). Using the 75kW as one example,(and if I use the data from a Siemens motor I have handy)the efficiency of the motor is 94.3%. This means that at full load the input power required to run this motor will be 75/0.943=79.53kW. The maximum losses are (79.53kW-75kW)=4.53kW. As mentioned earlier, the optimising function of a softstart will recover some of the fixed exitation losses, and these are typically 35% of a motors TOTAL losses=(4.53*0.35)=1.58kW. The PowerBoss that you are about to purchase will, they may claim, save 35%! This is 35% of your fixed exitation losses. Now we are getting closer to the real truth; 1.58 * 0.35= 0.553kW. This is it, at full load. So, now multiply the savings in kW (0.553) by your yearly running hours (say 8000 if running most of the time) by the tariff charge (no idea where you are but I'll guess the USA, so 10c/kWhr) and you get a typical yearly saving of $442 per annum. This is, by the way, assuming a controller at 100% efficiency. Take off 3% from your kW figures and you are somewhere close. You can work out the same at 3/4 load, assuming the efficiency of the motor is about the same.
Once you've done this, work out your Return and see if the sums add up.Take into consideration the running hours and I would doubt it.

 

[cbarn24050]

Your not going to make much saving on 70% load, savings really only come below 15%, even then its still very application dependent. Of course a lot depends on the cost of these units, shop around.

 

[jbartos]

Suggestion: Visit

http://www.somars.com/powerboss_the_product.htm

for:
Motors consume more electricity than everything else combined; yet international bodies calculate that over 50% of drivepower energy could be saved by improved efficiency.

It appears that the 50% of drive power energy could be saved by improved efficiency. It is necessary to properly interpret the 50%. For example, if the motor runs idle, its run has almost zero efficiency since the machine is idle and the motor might be disconnected from the load by some electromagnetic coupling. In fact, the motor propelling idle load, e.g. machine shop machine, waste a lot of energy since the machine shop machine can use very little extra energy when loaded, e.g. a large drill drilling small hole.
If such motor can be efficiently controlled perhaps to its stop, the energy savings will be large, e.g. 50% or more.

 

[Marke]

Hello sed2developer

One problem in your calculations, or perhaps the way that I read them, is that you imply that savins will be made at full load, 3/4 load etc when in reality, there will be an increase in losses at greater than 50% load. In reality, the maximum savings are under open shaft conditions and the amount saved (in kw) drops dramatically as the load is increased. Do not expect to see any savings when the power factor rises above around 0.4 - 0.5

Best regards,

Mark Empson

http://www.lmphotonics.com

 

[tmahan]

As Sed2developer mentions it is not simply enough to look at the "saved energy". the actual cost of the energy saved overtime must be discounted a some rate and compared over time to the cost of the NOLA based device.

An additional point to mention is the issue of heat generation. Consider the case of the 75kW motor ( I assume 400V) Under full load that is a current draw of approx 150A. If we consider the more or less ideal savings case for the NOLA device then the Motor is drawing around 50A. Each SCR has a .7V drop and there are 3 SCRS conducting that current at any given instant so the heat generated is about 105 watts. (these losses should also be considered in the cost calculations)

This heat must be dealt with in some way. In an industrial setting it is seldom possible to simply vent the enclosure. So either a special design (heatsink out the back), air conditioning or forced air ventilation with filters must be used.

The best device for saving power is an "OFF" switch. For a softstarter the second best method is a bypass contactor that operates at very nearly 100% eff.

This is in addition to the other problems describe in previous post such as harmonics ect...

 

[Marke]

Hello tmahan

The voltage drop across the SCRs is more likely to be in the 1.1 - 1.5 volt range depending on the brand of the SCR. If you have a source of SCRs with 0.7Volts loaded, let me know. We could reduce the heatsinking on soft starters!!
I always recommend to allow 4.5 wats per line amp (for three phase) when designing ventillation systems for soft starter applications.
Best regards,

Mark Empson

http://www.lmphotonics.com

 

[jraef]

It is curious to me that this subject is repeatedly brought up over and over in several public forums. Call me a conspiracy freak, but often I wonder if we are not all being unwittingly drawn into these discussions, thus keeping the subject active. This may actually be helping these questionable marketers to dupe their victims, er "customers", into a false sense of legitimacy!

If anyone actually did their research at this site, Marke's site or one of several others, they would see that the overwhelming majority of qualified electrical professionals see these "energy savers" as, at best, poor examples of engineering practice and at worst, borderline fraud.

Soft starters provide plenty of tangible and verifyable benefits. Energy savings is not one of them.

Quando Omni Flunkus Moritati

 

[cbarn24050]

Hi jraef, I think your being a bit harsh there, these devices do work but only when used in the right application. If you have the wrong application then you should fit high efficiency motors instead. Of course in " the land of cheap energy" its hard to justify on economic grounds but everyone else on the planet has to pay a lot more for their power.

 

[Marke]

Hello cbarn24050

I think that that is exactly the point. In the right application, they do work. It is just a pity that some of the promoters of this technology were not quoting more accurate figures.
It is not the technology that is wrong, it is the way the technology is promoted. As I always say, you can only save part of what is being wasted.
I agree with Jraef, a number of these discussions are started by the not so innocent trying for some free advertising. I have even fielded a few threats over my stance, but you cant really argue against the premise of saving what is wasted can you??
Best regards,

Mark Empson

http://www.lmphotonics.com

 

[jbartos]

Comment to cbarn24050 (Industrial) Nov 5, 2003 marked ///\\\
Hi jraef, I think your being a bit harsh there, these devices do work but only when used in the right application.
///Agreed. Your posting is an example of the mature engineering approach to the solution. The posting is more appropriate posting since the manufacturers of such devices may actually demonstrate the energy saving on the Client premises.\\ If you have the wrong application then you should fit high efficiency motors instead. Of course in " the land of cheap energy" its hard to justify on economic grounds but everyone else on the planet has to pay a lot more for their power.
///Right on!\\\

 

[jraef]

Just to follw up with a bit of clarification, I live in California (pronounced collie-for-nee-ahhhh as of yesterday). This is NOT the land of cheap energy!

Quando Omni Flunkus Moritati

 

[cbarn24050]

Hi Jreaf, how much do you pay per KWH?